Metadata Agents and
Semantic Mediation
Mikhaila Burgess
Cardiff University
BiodiversityWorld GRID Workshop
NeSC, Edinburgh – 30 June and 1 July 2005
Overview
•
•
•
•
•
•
•
BiodiversityWorld Metadata Repository
BDW Ontology
Chosen ontology tools
Ontology structure
Metadata Agents
Metadata in the BDW environment
Further developments
BiodiversityWorld GRID Workshop
NeSC, Edinburgh – 30 June and 1 July 2005
Metadata Repository (MDR)
• To store BDWorld metadata - “data about data”
• Composed of:
• Resource Registry
• BDWorld Ontology
• Ontology tools – inc access, update, query
• Access methods:
• Web front-end (eg Resource Registry)
• Ontology GUI
• Metadata Agents
BiodiversityWorld GRID Workshop
NeSC, Edinburgh – 30 June and 1 July 2005
Metadata Repository
• To allow resources to publish their metadata
•
•
•
•
Describe the type of resource
Supported operations
Supported data types
Access methods
• Supply information to workflow manager:
• Locating suitable resources & operations
• Ensure operation compatibility
• Manage workflow provenance information
BiodiversityWorld GRID Workshop
NeSC, Edinburgh – 30 June and 1 July 2005
Ontology: a definition
• “An ontology defines a common vocabulary for
researchers who need to share information on a
domain. It includes machine-interpretable definitions
of basic concepts in the domain and relations
among them.”
• Some reasons:
• Extracting domain knowledge (explicit, analysis)
• Reuse of domain knowledge
• Sharing common understanding of the structure of
information
BiodiversityWorld GRID Workshop
NeSC, Edinburgh – 30 June and 1 July 2005
Ontology: What is it?
• Ontology is a formal explicit description of:
• concepts in a domain of discourse (classes,
concepts) Entity/Object
• properties of each concept describing various
features and attributes of the concept (slots, roles,
properties) Attribute
• restrictions on slots (facets, role restrictions) Value
• Knowledge base - an ontology, with a set of
individual instances of classes/concepts
BiodiversityWorld GRID Workshop
NeSC, Edinburgh – 30 June and 1 July 2005
Why do we want an ontology?
• Storing and sharing of semantic information
• Answering questions:
• Which resources can provide information on
legumes?
• Find operations that are similar to a given
operation.
• Which operations accept map coordinates?
• Given a specific operation, which other operations
will accept its output?
BiodiversityWorld GRID Workshop
NeSC, Edinburgh – 30 June and 1 July 2005
Protégé & Jena
• Protégé
•
•
•
•
Open source ontology editor
Knowledge base framework
Number of plug-ins available
Customisable
• Jena
• Java framework for building Semantic Web apps
• Programmatic environment – RDF, RDFS, OWL
• Rule-based inference engine
BiodiversityWorld GRID Workshop
NeSC, Edinburgh – 30 June and 1 July 2005
Ontology Contents
• Resources
• Datatype: Name, Description, Type, Owner, …
• Object: Operation(s), Endpoint(s), …
• Operations
• Datatype: Name, Description, Usage, Num ports, …
• Object: Ports, Resource(s), Author/Owner, Similar
Operation(s), …
• Ports
• Datatype: Type, Optional, Default
• Object: Data type, Operation(s)
BiodiversityWorld GRID Workshop
NeSC, Edinburgh – 30 June and 1 July 2005
Ontology Contents
• Data Types
• Java, XML, etc
• Link to operations
• Acronyms: expansion, definition(s)
• Keywords
• Definition(s)
• Synonyms & Antonyms
• Similar terms
• Two levels of metadata …
BiodiversityWorld GRID Workshop
NeSC, Edinburgh – 30 June and 1 July 2005
Levels of Metadata
• Metadata - “data about data”
• Meta-metadata – data about metadata
• BDW metadata: Meta-metadata
• Resource Name
• Description
Ontology metadata
• MDR data: Metadata
• “AVH Database”
• “Australia's Virtual Herbarium”
BiodiversityWorld GRID Workshop
NeSC, Edinburgh – 30 June and 1 July 2005
Instance data
BDW Ontology in Protégé
Datatype property
Object property
BiodiversityWorld GRID Workshop
NeSC, Edinburgh – 30 June and 1 July 2005
Ontology Viewing
BiodiversityWorld GRID Workshop
NeSC, Edinburgh – 30 June and 1 July 2005
Ontology Viewing
BiodiversityWorld GRID Workshop
NeSC, Edinburgh – 30 June and 1 July 2005
Instances and Relationships
BiodiversityWorld GRID Workshop
NeSC, Edinburgh – 30 June and 1 July 2005
Terms/Keywords
BiodiversityWorld GRID Workshop
NeSC, Edinburgh – 30 June and 1 July 2005
Definitions
Related terms
Opposite
Interchangeable
The Ontology Online
BiodiversityWorld GRID Workshop
NeSC, Edinburgh – 30 June and 1 July 2005
Metadata Agents
• An interface to the MDR
• Multiple instances for a single MDR
• Primary role of Metadata agents:
• Resource Locating
• Resource Matching
• Resource Discovery
• Provide metadata and semantic information to
workflow manager
BiodiversityWorld GRID Workshop
NeSC, Edinburgh – 30 June and 1 July 2005
Initial Operation Set
• Vocabulary queries
• Retrieve all resource names
• Retrieve all operation names
• Selection queries
• Retrieve all resources meeting specific criteria
• Retrieve all operations with specific output
• Matching queries
• Which operations accept data type x?
• Which operations output specific data type?
BiodiversityWorld GRID Workshop
NeSC, Edinburgh – 30 June and 1 July 2005
How the MDR will fit into BDW
Workflow Manager
(Triana)
Wrapper(s)
User
Ontology GUI
Protégé
Inference
engine
Metadata Agent(s)
Multiple wrappers
& resources
JENA
Multiple instances
BDW Ontology (OWL)
Currently: OWL
Future: Database
BiodiversityWorld GRID Workshop
NeSC, Edinburgh – 30 June and 1 July 2005
Ontology Instance Data (Database)
Further Development
•
•
•
•
•
•
More work on inference engine (Jena)
Linking Metadata Agents to Jena
Refining/Improving ontology
Testing of resource registration methods
Storage of more metadata
Putting it all together – Semantic Mediation
BiodiversityWorld GRID Workshop
NeSC, Edinburgh – 30 June and 1 July 2005